Humidity and corrosion indicator



April 9, 1963 E. H. SCHELL 3,084,658

HUMIDITY AND CORROSION INDICATOR Filed April 20, 1960 4 2 I 7 l l ff A v L SENSING ELEMENT INVENTOR.

EDWARD H. SCHELL BY W4. A92- MAM c r! 9444 ATTORNEYS United States Patent 3,084,658 HUMlDlTY AND CQRRGSION INDTGATQR Edward H. Schell, 3613 Elderberry Ave., Dayton, ()hio Filed Apr. 20, 1960, Ser. No. 23,587 5 Claims. (Cl. 116-114) (Granted under Title 35, U.S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the United States Government for governmental purposes without payment to me of any royalty thereon.

This invention relates to a mounting means for supporting a moisture and corrosion indicator in packaged goods.

When hardware items are to be stored for an extended period of time, it is customary to package these items in containers placed in protective envelopes of material impervious to moisture. However, due to imperfect sealing of the packages, moisture does enter the packages and will result in damage in the form of rust to the hardware items therein.

Because of this problem, it is common to provide the packages with a moisture indicator means. The moisture indicator means may be in combination with a dehydrating means, both of which may be located in the wall of the packaged goods. By observing the change of color of the moisture indicating element in a container mounted in the wall of the package goods, pressure or absence of moisture at a particular moment may be determined. Moisture indicators commonly used, such as cobaltous chloride indicate only the presence or absence of moisture at a particular moment since the cobaltous chlorides color will change from blue to pink in the presence of moisture and upon the removal of the moisture the color of the indicator will change back to blue and the reversible process will continue on indefinitely. Since the process is reversible, visual inspection of the indicating element will not indicate how long moisture has been present and its efiect on the hardware items therein. Therefore, it is preferable that an indicator be used that more adequately reflects the chemical change that has taken place within the package.

In the instant application, the mounting means comprises an elastomeric grommet having a transparent window mounted therein upon which a moisture indicator is applied. The application of the grommet to an opening in a container wall is simplified as access to the inside of the package wall is unnecessary because the grommet may be securely fastened in sealing relationship by inserting it from the outside through the opening in the wall. Mounting means known heretofore were usually of the threaded metal humidity plug type wherein washers, nuts and the like were attached on the inside of the package wall making it necessary to break the package seal to enter and attach the mounting means to the package wall.

An object of this invention is to provide a simplified moisture indicator means having only two parts.

A further object of this invention is to provide a selfsealing mounting means for a moisture indicator.

A further object of this invention is to provide a mounting means which is relatively flush with the external surface of a container wall.

A further object of this invention is to provide a mounting means with a transparent window mounted therein for applying a moisture indicator on the underside thereof which may be visually seen from the outside of the container.

A further object of this invention is to provide a mounting means having a simplified construction which may be mass produced at a relatively low cost.

A further object of this invention is to provide a mountby a transparent disk ice ing means that may be quickly inserted and removed from an opening in a container wall.

The above objects and others may be fully understood and apreciated by referring to the single FIGURE in the drawing which is a cross-sectional view of the instant invention.

The instant invention as may be seen from the single view in the drawing comprises two parts and the indicator. The resilient elastomeric rubber grommet member 1 has an internally grooved central aperture that is sealed closed 2 the peripheral edge of which seats in the grommet aperture groove 8. The grommet member may be made from any suitable resilient elastomeric material such as rubber or plastic. Upon insertion of the grommet into an opening in the panel or container wall 3, the peripheral shoulder 5 compresses inwardly until it has passed the portion of the container wall defining the opening with the grommet groove 4 housing the hole edge of the container wall and then the grommet shoulder expands into sealing relationship with the container wall.

A peripheral flange 7 cooperating with the peripheral shoulder 5 will provide a positive airtight fit between the container wall 3 and the grommet 1. To retain the flat smooth container surface 3, the flange 7 is made relatively thin. Groove 8, which receives the transparent disk 2, is located in the internal surface of the grommet body 1 in a plane common to the container wall 3. Depending upon the indicator element 6 applied to the under surface of the transparent disk 2, the disk may be made from any suitable material such as Plexiglas or ordinary borosilicate glass used in microscope slides.

The sensing element 6 on the underside of the disk substrate 2 may be either a film of cobaltous chloride or a metallic film between 500-1000 angstroms in thickness. When a visual indication of the amount of humidity at a particular moment is desired, the cobaltous chloride is preferable to a metal fihn as a sensing element. Where it is desired to know the amount of moisture integrated over a period of time, the metal film sensing element will provide the only satisfactory indication since the metal film will corrode producing rust as long as moisture is present in the container. Pure iron is preferable as a metal film indicating element since it readily forms iron oxide which may be visually seen when looking through the transparent disk substrate 2. Magnesium may, as an alternative, be used as a metal sensing element when conditions warrant its use.

Cobaltous chloride as an indicator may be employed alternatively as a third part of the assembly in the form of a disk of porous material impregnated with cobaltous chloride. The disk, as for example, may be fabricated from blotter paper and secured below the substrate 2 by engagement with the peripheral slot 8 and/ or to the substrate by adhesive or glue between the substrate and porous disk. This embodiment has the advantage of being easily serviced when a replacement sensing element is required since the sensing element being replaced may be removed and a replacement easily inserted in its place.

It is to be understood that the form of the invention herewith shown and described be taken as a preferred example of the same and that various changes in the size, shape and arrangement of the parts may be resorted to without departing from the spirit of the invention or the scope of the appended claims.

1 claim:

1. A moisture and corrosion indicator mounting means for indicating the presence of moisture within a container having a moisture impervious wall into an aperture in which container wall the indicator mounting means is installed and is removed from outside the container, the indicator mounting means comprising (a) an outwardly grooved and shouldered and inwardly apertured and aosaees grooved resilient rubber grommet, (b) a downwardly and inwardly tapered friction surface compressible frustoconical portion of the grommet outer surface extending upwardly as a shoulder grommet portion that compresses inwardly as the grommet is forceably inserted into the grommet receiving aperture in the container wall and then expands beneath the container wall in sealing relationship therewith as the outer peripheral groove in the grommet outer surface houses the container wall in sealing engagement therewith, (c) a transparent disk in the grommet central aperture with its edge disposed in the grommet inward groove in sealing relationship therewith, and (d) a moisture sensitive indicator disposed within the container and visible through the transparent disk.

2. A humidity sensitive device comprising:

(a) a one-piece rubber ring continuous circular wall with a pair of axially aligned grooves on radially opposite sides of the ring wall and extending continuously completely around the ring; and

(b) a humidity sensitive circular visually apparent disk with its edge in the radially inner wall surface groove in sealing relation with the ring.

3. A rubber grommet device comprising:

(a) a one-piece circular rubber ring body provided with a body radially inner groove and a body radially outer groove aligned axially with the inner groove;

(b) a peripheral flange of the rubber ring body on one axial side of the outer groove;

(0) an upwardly diverging and downwardly converging frusto conical rubber grommet lower body portion below the pair of axially aligned grooves and having an inner cylindrical surface and an outwardly peripheral rounded shoulder on the side of the outer groove remote from the peripheral flange;

(d) a transparent disk with its peripheral edge seated in the inner groove in hermetically sealing relation with the rubber ring body; and

(e) an optically apparent film of oxygen and water vapor sensitive material adhered to the surface of the transparent disk in the side of the disk that is remote from the peripheral flange.

4. The device described by the above claim 3 with (f) a layer of cobaltous chloride adhered to the surface of the transparent disk as the oxygen and water vapor sensitive material.

5. The device described by the above claim 3 with (g) a film of iron adhered to the surface of the transparent disk as the oxygen and water vapor sensitive material.

References Cited in the file of this patent UNITED STATES PATENTS s l a 

1. A MOISTURE AND CORROSION INDICATOR MOUNTING MEANS FOR INDICATING THE PRESENCE OF MOISTURE WITHIN A CONTAINER HAVING A MOISTURE IMPREVIOUS WALL INTO AN APERTURE IN WHICH CONTAINER WALL THE INDICATOR MOUNTING MEANS IS INSTALLED AND IS REMOVED FROM OUTSIDE THE CONTAINER, THE INDICATOR MOUNTING MEANS COMPRISING (A) AN OUTWARDLY GROOVED AND SHOULDERED AND INWARDLY APERTURED AND GROOVED RESILIENT RUBBER GROMMET, (B) A DOWNWARDLY AND INWARDLY TAPERED FRICTION SURFACE COMPRESSIBLE FRUSTOCONICAL PORTION OF THE GROMMET OUTER SURFACE EXTENDING UPWARDLY AS A SHOULDER GROMMET PORTION THAT COMPRESSES INWARDLY AS THE GROMMET IS FORCEABLY INSERTED INTO THE GROMMET RECEIVING APERTURE IN THE CONTAINER WALL AND THEN EXPANDS BENEATH THE CONTAINER WALL IN SEALING RELATIONSHIP THEREWITH AS THE OUTER PERIPHERAL GROOVE IN THE GROMMET OUTER SURFACE GOUSES THE CONTAINER WALL IN SEALING ENGAGEMENT THEREWITH, (C) A TRANSPARENT DISK IN THE GROMMET CENTRAL APERTURE WITH ITS EDGE DISPOSED IN THE GROMMET INWARD ROOVE IN SEALING RELATIONSHIP THEREWITH, AND (D) A MOISTURE SENSITIVE INDICATOR DISPOSED WITHIN THE CONTAINER AND VISIBLE THROUGH THE TRANSPARENT DISK. 